The use of thoracic catheters (also referred to as a chest drain, chest tube, intercostal drain, tube and tube thoracostomy) is widely known, and became popular after the widespread use during the World War II and the Korean War. A thoracic catheter is known as a flexible/semi-flexible tube which is inserted into the chest cavity (pleural and/or pericardial space) and is used to remove/evacuate air (pneumothorax) or fluids (blood, effusion, chyle or pus) from such cavities.
Common indications for thoracic catheter insertions include but are not limited to presence of pneumothorax, tension pneumothorax, large pleural effusions, chylothorax, hemothorax, and empyema. Thoracic catheters are frequently used in the postoperative setting following a thoracotomy, esophagectomy, video-assisted thoracoscopy surgery (“VATS”) and cardiac surgeries. Once the thoracic catheter or chest tube is in place, it is sutured or otherwise attached to the skin to prevent movement. The chest tube is then connected to the drainage container (e.g., a canister) using additional tubing and connectors. The canister may also be connected to a suction source (e.g., negative 20 cm of water pressure) or it may be left on a water seal.
Drainage of the pleural space by means of a thoracic catheter is the most common intervention in thoracic trauma, and there are more than one million thoracic catheters that are placed annually in the United States.
Despite the fact that thoracic catheters are used quite commonly worldwide, an ideal functioning design for the device has proven thus far stubbornly elusive, regardless of the significant market forces motivating such an improvement. The most frequent complication associated with a thoracic catheter is clogging or blockage of the catheter lumen by thrombus formation or debris that is inside the catheter lumen. This clogging can cause major subsequent complications and non-functioning or malfunctioning of the tube. The presence of a clot inside the catheter lumen can also cause stasis of the drainage, cause infections and/or deterioration of infections (e.g., in cases with empyema). One prospective study reported a thirty-six percent rate of clogging and non-functioning of the thoracic catheter in patients undergoing cardiac surgeries. [J. R. Karimov, et al. Incidence of chest tube clogging after cardiac surgery: a single-centre prospective observational study. Eur. J. Cardiothorac. Surg. 44(6):1029-36 (2013).] This complication was reported to be more common in urgent procedures and/or reoperations and in cases with increased intra-operative blood transfusions. Such clogging was also associated with a higher risk of atrial fibrillation development in the patient, which could potentially be a lethal complication. Interestingly, more than eighty percent of the clogging in the thoracic catheter was found to be in the internal portion of the tube (i.e., the non-visible or intra-thoracic portion that is inside the patient's chest cavity), which makes the diagnosis of this complication by bedside visualization and or inspection very difficult or impossible.
Due to the same reason, management of this complication can be complex and challenging. The thoracic catheter can become clogged at any time after its placement, and it is known that clinicians generally underestimate the prevalence of this failure to drain. Clogging of the tube can even become life threatening in cases where bleeding in the chest goes undiagnosed due to lack of drainage. When a thoracic catheter clogs, it can cause accumulation of blood around the heart (pericardial tamponade) and the lungs (hemothorax). In case of the pneumothorax, blockage in the thoracic catheter can cause tension pneumothorax, which is life threatening.
In a survey which included North American cardiothoracic surgeons and specialty cardiac surgery nurses, 100% of the responders confirmed that they have had problems with thoracic catheters getting clogged and (87%) reported adverse patient outcomes from a clogged tube. [S. Shalli, et al. Chest tube selection in cardiac and thoracic surgery: a survey of chest tube-related complications and their management. J. Card. Surg. 24(5):503-9 (2009).] More than 50% of the participants confirmed that they are not satisfied with currently available chest tubes and procedures to avoid chest tube occlusion. Some of the responders even mentioned that they forbid the current technique for unclogging thoracic catheters, namely the stripping, tapping, and/or squeezing maneuver, for fear of causing more bleeding by the negative pressures generated. In addition, the survey respondents noted that patients experience increasing discomfort with increasing drain size and did not think that increasing the size of the thoracic catheters was a good strategy to prevent clogging of the tubes. The conclusion of the survey highlighted the frequent clogging problems with current postsurgical chest drainage systems and observed a pressing need for new and innovative solutions to prevent clogging complications and to address clinician concern and patient pain.
Another challenge with the current thoracic drainage system is when a patient who already has a thoracic catheter in place requires a video-assisted thoracoscopic surgery (“VATS”) procedure. For the VATS operation, in the current practice, the surgeon is taught to make additional incisions (“port sites”) and insert ports, which are used for entry of a camera and instruments. The inventors noted that a single incision VATS, which would spare the patient from having extra incisions and/or port insertions while undergoing VATS would be ideal, as it would decrease postoperative pain and result in a higher patient satisfaction compared with the conventional three-port VATS. The inventors also realized that a thoracic catheter should be designed that could also function as the lone port for a single incision VATS, which would spare the patient even from a single extra port. Outside experts in the field of thoracic catheters have expressed skepticism of single incision VATS due to current technological limitations.
As the above description clearly shows, there is a long felt and unresolved need for a better designed thoracic catheter, including methods and devices to help detect and/or prevent blockages in such catheters and providing the capability to use such catheters as port site when performing VATS procedures.